Lining or coating vulcanized plates with metal.



No. 652,752. I Pafented July 3,1900. J., A. DALY.

LINING OB COATING VULCANIZEDPLATES WITH METAL.

(Appficntion filed Aug. 8, 1899. (N0 Model.)

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" UNITED 'Sfrafrles JOHN A. DALY, OF \VASHINGTON, DISTRICT OF COLUMBIA.

LINING OR COATING VULCANIZED PLATES WITH METAL.

SPECIFICATION forming part of Letters Patent No. 652,752, dated July 3,1900.

Application filed August 8, 1899. fierial No. 726,569. (No specimens.)

T0 ctZZ whom it may concern.-

Be it known that I, JOHN A. DALY, a citizen of the United States,residing at Washington, in the District of Columbia, have inventedcertain new and useful Improvements in Lining or Coating VulcanizedPlates with Metal, of which the following is a specification, referencebeing had therein to the accompanying drawing.

This invention relates to a method of lining or covering the whole or apart of vulcanized dental plates or similar articles with a metalliclining or covering.

The object of this invention is to provide a cheaper method of lining orcovering vulcanized plates than that described in my application SerialNo. 678,266, filed April 20, 1898, for lining dental plates. In saidapplication the salient feature of improvement consists in filling thespongy face of a foil having one spongy face with a vulcanizablecompound and vulcanizing the same onto a previously-vulcanized plate.

The drawing illustrates a section of a dental plate somewhat exaggeratedas to proportions, showing the arrangement of layers prior to the finalvulcanization.

The patent to Starr, No. 413,376, of October 22, 1889, describes amethod of lining dental plates with a compound foil consisting of asheet of silver foil or leaf united to a sheet of gold foil or leaf.This silver-gold foil was placed with the silver side in contact withthe rubber in the vulcanizer and the whole then vulcanized. The attackof the sulfur in the rubber compound on the silver of the compound foilis supposed to turn the silver into a sulfid, which forms a mechanicalunion with the gold and with the rubber and unites the two together. Thesaid Starr claims the improvement in the art of lining rubber dentalplates which consists in applying a compound foil to the rubber prior tovulcanization and uniting it thereto by converting the silver into asulfid during the vulcanizing process, substantially as described.

The patent to Barnes, No.348,183,of August 31, 1883, describes acompound metallic foil, one face being gold, the other tin, which may beelectrodeposited on the gold, in which case the tin will be porous orspongy. A layer of gutta-percha is used to attach the tinned side of thecompound foil to the rubber dental plate, and the whole is vulcanizedtogether. As stated in the patent and as explained by Mr. Barnes, thefoil was placed on the rubber prior to vulcanization.

In certain abandoned applications for patent filed by me some fifteenyears prior to the present application I described a compound foil madefrom a sheet of gold-foil and having one roughened surface made byattaching particles of bronze or metallic powder to the gold-foil bysolder or the like or a surface of solder. From this it will appear thatI am wellaware that a compound foil having one surface of gold and theother surface of a baser metal 'or material is not new. Such a compoundfoil of any known or usual construct-ion I do not herein claim; but suchmay be used with my present invention.

l The objection to the coating of a dental plate with a compound foilhaving one gold face and one baser face has heretofore been that thelarge amount of sulfureted hydrogen or other gas developed from theprepared rubber in vulcanizing would frequently wholly destroy the basermetal, leaving the gold film unattached or but slightlyattached to theplate. Again, as a dental plate is not of uniform thickness some partsof the plate develop more of the solvent gases than do other parts andthe base metal is more eaten away at one part than at another, producingplates .which soon lose their linings or coverings in spots, if they arenot spotted when removed from the vulcanizer. I overcome theseobjections to the use of compound foils as a lining or covering forvulcanized rubber plates in the following manner:

I make acomplete rubber dental or similar vulcanized plate byany of theusual processes, or I take any common rubber dental or similarvulcanized rubber plate which may have been made and used for years. Ifthe plate is in any manner impure I treat it with alkali or otherchemical agent, eithercold or hot, and dry the plate, so that the plate'is clean and sweet. I then cover such parts of the vulcanized rubberplate as are to be covered with metal with a thin coating of wtcanizable rubber, gutta-percha, or the like. This may be laid on with abrush, if in liquid form, or a thin sheet of the dry material may belaid on the plate, or, as 'an equivalent step, the vulcanizable materialmay be .applied as i a coating to the baser-metal face of the compoundfoil. pound foil is then placed on the vulcanized plate and rubbed downthereon. The sticki- The base-metal face of the comness of theunvulcanized material willattach i the foil to the plate, and then theplate and coating maybe simply embedded in a mass of 1 soft or wetplaster-of-paris, no prepared mold being necessarythat is, the dental orother plate may be put in a vulcanizer and plaster poured around it andallowed to harden. When the plaster has set, the vulcanizer,with f itsinclosed contents, is exposed to the usual vulcanizing heat for a fewminutes. With a silver-gold foil one to three minutes will usually besufficient.

WVitha gold-tin foil 3 three to ten minutes may suffice. With nickel orbronze on gold different periods of time will be necessary, although nogreat damage will occur if the time be longer than the periodsmentioned. The time required for vulcanization is much less than thatusually Tcquired to vulcanize a plate. The previouslyvulcanized platethrows off very little of the ignored. The thin coating of vulcanizablematerial throws oif .gas which attacks the base metal or baser face ofthe foil and eats into or roughens it or renders it porous. As thesolvent gases, and this gas may generally be 7 quantity of gas thrownoff from the thin film is small, it does not wholly destroy the basemetal or baser face of the foil. Moreover, as

the vulcanizable coating is of a practicallyuniform thickness the gasesattack all parts of the base metal or base face of the foil.

plate will have become vulcanized to both plate and foil, making a veryfirm union which is practically uniform throughout the 3 coated surface,owing to the uniform thickness of the coating or attaching materialwhich forms the bond of union between the 3 foil and the plate and theshort time of the second or lining vulcanization.

The distinction I have endeavored to make clear between the presentprocess and various old and known processes is that heretofore the foilhas been attached to the material to be vulcanized before vulcanizationand was unequally acted on by the gases developed in vulcanization ofdifierent thicknesses of material, and the baser metal was frequentlyentirely destroyed in patches by the large amount of gases so developed,whereas in the present process the main part of the vulcanization of theplate has been done before the foil was applied, and the very slightdevelopment of gas from a revnlcanization of such vulcanized plate isnot very material. The slight and uniform development of gas from thethin coating or sheet I apply is insufficient to destroy the base=metallayer of the foil, but is sufiicient to either roughen or chemicallychange the base metal, and the vulcanization firmly unites the foil tothe plate, as stated.

It is within the contemplation of my invention that the baser foil maybe attached to the vulcanized plate in the manner described,and the goldfilm may beafterward deposited thereon by electrodeposition. When thisis burnished down, afairly-sound face of gold can be produced.

What I claim is-- l. The method of attaching a compound foil to a dentalor similar rubber plate,which consists in inclosing a limited quantityof coating or vulcanizable material between a previously-vulcanizedplate and the basermetal face of a metal foil or film, and developing bythe heat of vulcanization a gas which attacks and partially destroys orchanges such baser-metal face, thereby causing the attachment of thefoil to the plate, substantially as described.

2. The method of covering a vulcanized dental plate with a foil whichconsists in cleansing the plate by means of a chemical agent, attachinga foil having a comparatively base metal face to the plate by means of athin layer of unvulcanized material interposed between the vulcanizedplate and the base-metal face of the foil, embedding the whole in softplaster, and vulcanizing, all substantially as described.

In testimony whereof I aflix my signature in presence of two witnesses.

JOHN A. DALY.

Witnesses:

W. A. BARTLETT, S. A. TERRY.

